Bacteria Gram stain

Gram negative. Bacteria that fail to retain Gram stain. This group includes the genera Salmonella, Pseudmonas, Pasteurella, Escherichia, and Brucella. 

Same pathogenic bacteria seen on Gram-stain, add 1 additional point... 

If CSF Gram stain and/or culture is negative, rapid diagnostic tests (such as latex agglutination) may be useful these tests are positive even if bacteria are dead. 

Ascitic fluid usually contains greater than 300 leukocytes/ mm3, and bacteria may be evident on Gram stain of a centrifuged specimen. 

Alternatively, a Gram stain vaginal smear may be used to diagnose BV using the Nugent criteria. This relies on estimating the proportions of bacteria morphotypes to provide a score between 0 and 10. A score of less than 4 is normal, 4 to 6 is intermediate, and greater than 6 is consistent with BV. 

Tlie morphology of some bacteria, especially those that form spores, is distinctive enough under the light microscope to have value for identification. This means that differential staining techniques, such as the Gram stain or acid-fast stain, and fluorescence microscopy may help to determine the iden-... 

Holm, C. Jespersen, L. A flow-cytometric gram-staining technique for milk-associated bacteria. Appl. Environ. Microbiol. 2003, 69, 2857-2863. 

Infected body materials must be sampled, if at all possible or practical, before the institution of antimicrobial therapy, for two reasons. First, a Gram stain of the material may reveal bacteria, or an acid-fast stain may detect mycobacteria or actinomycetes. Second, a delay in obtaining infected fluids or tissues until after therapy is started may result in falsenegative culture results or alterations in the cellular and chemical composition of infected fluids. 

A standard urinalysis should be obtained in the initial assessment of a patient. Microscopic examination of the urine should be performed by preparation of a Gram stain of unspun or centrifuged urine. The presence of at least one organism per oil-immersion field in a properly collected uncentrifuged specimen correlates with more than 100,000 bacteria/mL of urine. 

Gram-Negative Refers to the inability of many bacteria to retain crystal violet or similar stain through the standard Gram stain procedure. They show only the red counter-strain. 

Gram Stain A staining procedure used in classifying bacteria. A bacterial smear on a slide is stained with a purple basic triphenyl methane dye, usually crystal violet, in the presence of iodine/potassium iodide. The cells are then rinsed with alcohol or other solvent, and then counter-stained, usually with safranin. The bacteria then appear purple or red according to their ability to keep the purple stain when rinsed with alcohol. This property is related to the composition of the bacterial cell wall. 

This classification is based on various criteria, including shape of the bacterium (rod, cocci) and the ability of the bacteria to be stained with a crystal violet-iodine complex in the presence of alcohol (Gram staining). This classification system also contains rickettsiae and chlamydiae both of these tend to be at the interface with viruses in that they are intracellular bacteria. 

A clinical diagnosis of bacterial meningitis was made. Therapy was started immediately because of the life-threatening nature of the illness. He was empirically treated with ceftriaxone and vancomycin, intravenously. A short time later, a Gram stain of his CSF revealed that the bacteria were Gram-positive cocci. Accordingly, the empiric... 

Dyes have a long history of use in medicine both for diagnostic and therapeutic purposes. Thus, crystal violet (76) is used for staining bacteria (Gram test), and the azo dye Prontosil rubrum (77) was the first drug that produced the active agent sulfanilamide (78) on reduction in the body [67],... 

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